Vibrating mill with heat insulating grinding chamber

ABSTRACT

A vibrating mill is provided with horizontally disposed grinding chambers arranged in vertically spaced parallel relation one above the other and surrounded each by a heat insulating jacket and mounted fixedly as a unit in a vibrating supporting frame. For the purpose of keeping the vibrating stresses away from the heat insulating jackets and for eliminating heat losses as much as possible, the supporting frame is rigidly connected with the outer wall of the grinding chamber by special connecting means made of a material having not only heat insulating properties but also a good mechanical strength at low temperature. The connecting means are arranged in an annular space provided between the exterior wall of said grinding chamber and said supporting frame and extend through the wall of the heat insulating jacket. These connecting means are in part made of hard polytetrafluoroethylene and may also comprise radial distance members made of a ceramic material, quartz glass or a special technical glass of high strength.

United States Patent 1191 Haas et a1.

1 1 VIBRATING MILL WITH HEAT INSULATING GRINDING CHAMBER [75] Inventors:Helmut Haas; Giinter Eichholz, both of Koln, Germany [73] Assignee:Klockner-Humboldt-Deutz Aktiengesellschaft, Koln, Germany [22] Filed:Dec. 27, 1971 [21] Appl. No.: 212,326

Primary Examiner-Al Lawrence Smith Assistant Examiner-Gary L. SmithAttorney, Agent, or Firm-Hill, Gross, Simpson, Van Santen, Steadman,Chiara & Simpson 1 Oct. 1,1974

157 V l ABSTRACT A vibrating mill is provided with horizontally disposedgrinding chambers arranged in vertically spaced parallel relation oneabove the other and surrounded each by a heat insulating jacket andmounted fixedly as a unit in a vibrating supporting frame. For thepurpose of keeping the vibrating stresses away from the heat insulatingjackets and for eliminating heat losses as much as possible, thesupporting frame is rigidly connected with the outer wall of thegrinding chamber by special connecting means made of a material havingnot only heat insulating properties but also a good mechanical strengthat low temperature. The connecting means are arranged in an annularspace provided between the exterior wall of said grinding chamber andsaid supporting frame and extend through the wall of the heat insulatingjacket. These connecting means are in part made of hardpolytetrafluoroethylene and may also comprise radial distance membersmade of a ceramic material, quartz glass or a special technical glass ofhigh strength.

6 Claims, IZ Drawin g riglii PATENTED BET 1 74 SHEET 10F 6 FIG. 3

PATENTEDBEH 1914 r 3,838,825

SHEEI 50F 6 A FIGH PATENTED BET 1 1974 SHEET 6 0f 6 FIGJZ VIBRATING MILLWITH HEAT INSULATING GRINDING CHAMBER The invention relates to avibrating mill provided with at least one horizontally disposedlongitudinal grinding chamber which is surrounded by an insulatingjacket and is secured to a frame which is yieldably mounted and isprovided with a vibratory drive.

In vibrating mills whose grinding chamber is sur rounded by aninsulating jacket, as is for instance customary in grinding operationsduring which refrigerants are introduced into the grinding chamber, itis difficult to secure the grinding chamber to the supporting frame.Owing to the low degree of strength of the customary insulating jacketswhich are employed and which consist, for instance, of polyurethanefoam, polystyrol, etc., it is not possible to connect the grind ingchamber by means of the insulating jacket directly with the supportingframe because the high accelerating forces which are produced during thegrinding operation would destroy the mentioned insulating materials veryquickly when they are used for transmitting the mentioned acceleratingforces.

When performing grinding operations at very low temperatures, it is alsodifficult to connect the grinding chamber with its outer wall to thesupporting frame be cause the customary types of steel which are beingused do not have a sufficient strength at low temperatures and anyspecial types of steel which have the strength to endure lowtemperatures are expensive and difficult to work.

It is an object of the invention to provide a vibrating mill with aheat-insulated grinding chamber which on the one hand is provided with arigid connection between the supporting frame and the grinding chamber,and on the other hand, does not cause any cold losses or at leastreduces the same substantially,

In accordance with the invention, a space is provided between the outerwall of the grinding chamber and the supporting frame, and within thisspace are arranged one or more connecting means having heat insulatingproperties and which are also of sufficient strength to transmit theaccelerating forces from the supporting frame to the grinding chamber.When these connecting means are employed and when, for instance, thedistance between the outer wall of the grinding chamber and thesupporting frame is substantially as great as the thickness of theinsulating jacket, then cold losses" will also be avoided within therange of the connecting means between the grinding chamber and thesupporting frame without the necessity of using the insulating jacket asa connecting means between the grinding chamber and the supportingframe.

Another advantage when using the connecting means of the invention isthat solely the grinding chamber and the connecting means have to bemade of materials which are able to endure low tempertures, while thesupporting frame and the associated connecting and tensioning elementsmay be made of conventional steel. In this manner, it ispossible-particularly in connection with vibrating mills in which thegrinding chamber is connected only by force-locking connecting meanswith the supporting frame to employ these vibrating mills subsequently,for instance for low temperature grinding operation because it is onlynecessary to exchange the grinding chamber, while all other parts of thedevice may be used as heretofore.

According to one embodiment of the invention, each connecting means mayhave the form of one part or multiple part band which is placed aroundthe outer wall of the grinding chamber. In this type of connectingmeans, it is possible in the present-day tubular vibrating mills toemploy connecting members which are made of a heat insulating materialhaving sufficient strength and are placed in the form of an annular orcollarshaped band at the connecting point on the supporting frame aroundthe grinding tube and which are adapted to be secured force-lockingly ina simple manner by customary clamping rings in suitable recessesprovided in the support frame. Depending upon the size of the diameterof the grinding tube, the annular or collar shaped band may be made of asingle piece or may be subdivided into a number of pieces in order tofacilitate the assembly of the construction. The insulating of thegrinding chamber is taken over at these connecting points by the band,while the other parts of the wall of the grinding chamber are surroundedby an insulating jacket of customary insulating material. At the sametime, the band serves also the purpose of transmitting the acceleratingforces.

It is also an object of the invention that in the event that aband-shaped connecting means is used, a continuous band or a subdividedouter and also an inner band is being used; these two bands beingarranged concentrically with respect to one another and being radiallyspaced, whereby in the annular space between these two bands,circumferentially spaced distance members are inserted which are usedfor transmitting the accelerating forces. This particular constructionhas the advantage that owing to the two concentric bands, a sufficientpressure distribution surface is created at the outer wall of thegrinding chamber which in the range of the connecting means is able toreduce and compensate the forces acting on the outer wall of thegrinding chamber. The arrangement of the distance members between theouter band and the inner band further more creates a crosssection whichreduces the heat transmission from the outside to the inside much betterthan a closed annular band would do. In fact, the insulation at theconnecting point is much improved since the possibility exists ofconnecting the insulating jacket directly with the annular band and onemay even place insulating material in the spaces between the individualdistance elements which connect the two annular bands with each other.

It is also an object of the invention to make the distance elements ofthe connecting means of another, preferably a harder material than theouter band and the inner band. This particular construction of theinvention has the advantage that between the outer wall of the grindingchamber and the corresponding engaging surface of the supporting frame,relatively large intermediate spaces are formed at the point ofconnection, so that relatively large spaces are available for theindividual distance elements between these two annular bands.

According to a preferred embodiment of the invention, the inner band andthe outer band of the connecting means are made of a plastic of highstrength and low thermal conductivity, preferablypolytetrafluoroethylene (PTFE) or hexafluoropropylene (FEP), while thedistance elements therebetween are suitably made of a ceramic material,such as porcelain or quartz glass, or special technical glasses having ahigh strength, or similar materials. When this is done. one makes use ofthe advantage that such plastic materials even at a very low temperaturestill have a certain elasticity, so that surface irregularities in thehard, but in some cases, brittle material of the distance elements arecompensated so that any extremely high stressed points in the materialare avoided. At the same time, this particular feature avoids thedisadvantage that even the elasticity still present at the lowtemperature in the plastics at the relatively long distance elements mayfail to effect a sufflcient clamping connection be tween the grindingchamber and the supporting frame.

In another embodiment of the invention the connecting means comprises aflexible band which extends around the grinding chamber incircumferential direction and is alternately attached to the grindingchamber and also directly to the supporting frame or to a specialclamping means attached to the supporting frame, so that so to speak,the flexible band extends zigzagshaped along the annular space formedbetween the grinding chamber and the supporting frame. In such aconstruction, one may select for the flexible band a material having arelatively high heat conductivity without risking any substantial coldlosses because any possible heat flow in view of the smallcross-sectional flexible band and the minor engagement surface at theattachment points on the supporting frame and the outside of thegrinding chamber, is very small. In this particular construction, it isadvisable to provide the flexible band with a tension means, so that thehighest possible tension may be adjusted when the operating temperatureis reached under due consideration of the contraction of the flexibleband material.

In a modification of this last described construction, it iscontemplated to fill the annular space within the range of the flexibleband with insulating material. Preferably one employs for this purposean insulating material having the form of a powder or the form ofgranulate. This has the advantage that in the event of a breakage of theflexible band, the grinding chamber will not directly hit the supportingframe or the supporting ring but will encounter the cushioning effect ofthe insulating material, so that a complete destruction of theconnecting means is avoided. On the other hand, such a type ofinsulating material may easily be removed from the annular space for thepurpose of making repairs.

According to another embodiment of the invention, the grinding chamberat the connecting point with the supporting frame may be connectedrigidly with a connecting element which extends only partially throughthe thickness of the insulating jacket, and is held by means of aclamping strap or stirrup in the supporting frame, whereby the contactsurfaces with the clamping stirrup and the engagement surface of thesupporting frame have parts which are partially hollow and are providedwith feed and discharge means for a heat carrier. In this manner, it isthen possible on the one hand, to limit the temperature losses to aminimum when the insulating jacket is closed around the grindingchamber, whereby the material employed for the insulation may beselected principally under due consideration of its insulatingproperties, while its strength plays only a subordinate roll. On theother hand, there is provided a rigid connection between the supportingframe and the grinding chamber which assures the transmission ofsufficient accelerating forces from the supporting frame directly to thegrinding chamber, and of course also a transmission of these forces tothe grinding bod ies in the grinding chamber. When the connectingelements in the range of their engaging surfaces are made hollow and areprovided with feed and discharge means for a heat carrier, it ispossible, for instance to maintain in the grinding chamber a temperatureof below 0C by the addition of heat which raises the temperature at theengagement surfaces of the connecting elements so that the strength ofthe materials used for the connect ing means and for the supportingframe is not adversely affected. This feature makes it possible toemploy the foundation frame, the supporting frame and the connectingmeans of a conventionally constructed vibrating mill unchanged, and whenthe operation, for instance, is converted to one which requires theaddition of refrigerants, it is only necessary to exchange the grindingchamber of this vibrating mill for another one, leaving all other partsthe same.

In another preferred embodiment of the invention, the cross-sectionalarea of the parts of the connecting elements which extend through theinsulating jacket is made smaller within the insulating jacket than atthe engagement surface with the clamping stirrup and the supportingframe. In such a construction, the heat losses which usually are causedby the rigid connection between the supporting frame and the grindingchamber are reduced to a far-reaching extent.

The invention provides also that the parts of the connecting means whichengage the supporting frame are provided with conduits which at theirends are connected with a feed and discharge device for a heat carrier.This arrangement of conduits for the purpose of permitting the passageof a heat carrier does not decrease the required strength of theconnecting means in the range of these contact surfaces for transmittingthe accelerated forces produced by the vibrating supporting frame andfor transmission to the grinding chamber.

In a preferred embodiment of the last mentioned construction of theinvention, the conduits in the mentioned parts of the connecting meansextend substantially parallel to the longitudinal axis of the grindingchamber. This arrangement produces the shortest possible length of thepath for the heat carrier, so that temperature differences of the heatcarrier between the inlet of the conduits and the outlet of the conduitsremain substantially small.

Since in individual cases, it may happen that along the circumference ofthe grinding chamber different temperatures may exist, it is advisableto provide the conduits individually or in groups with feed means anddischarge means, respectively, for the heat carrier. In this manner itis possible, for instance, to supply the upper portion of the horizontalgrinding chamber with a heat carrier which heats this upper portion to adifferent temperature than the lower portion of the grinding chamber.

In a preferred embodiment of the invention, when the conduits areapproximately all parallel to each other, one may connect these conduitsalternately on one end and then on the other end with feed means for theheat carrier, so that a counter-flow effect takes place. This has theresult that, when viewed in the longitudinal direction of the grindingchamber, a uniform temperature is created in the surface of theconnecting means which engages the supporting frame.

According to another feature of the invention, all of the conduits, atleast at their discharge end, are connected with each other by a commonconnecting conduit.

In particular, in such vibrating mills in which the I grinding chambershould have a temperature which lies below the temperature of theenvironment, the invention provides that the surfaces of the connectingelements which engage the supporting frame are provided with embeddedelectric resistance heating means.

Finally, the invention provides, at least in one of the clampingstirrups, a thermometer probe which is connected with a regulating meanswhich in turn adjusts the temperature of the heat carrier to apredetermined value.

The invention will now be described with reference to the accompanyingdrawings which illustrate by way of example a number of embodiments ofthe vibrating mill of the invention.

FIG. 1 illustrates diagrammatically a tubular vibrating mill providedwith two horizontal grinding tubes arranged in spaced parallelrelationship one above the other.

FIG. 2 illustrates one embodiment of a connecting means between thesupporting frame and one grinding tube in an enlarged scale along theline II-II of FIG. 1.

FIG. 3 illustrates another embodiment of the connecting means likewisein a cross-sectional view similar to FIG. 2.

FIG. 4 illustrates a portion of a longitudinal sectional view of theconnecting means illustrated in FIG. 3.

FIG. 5 illustrates in cross-section and in similar mannet as the FIGS. 2and 3, another connecting means comprising a flexible band.

FIG. 6 illustrates in a longitudinal sectional view along the line VI-VIof FIG. 5, a connecting means provided with an eccentric tensioningdevice.

FIG. 7 illustrates in a longitudinal sectional view, a connecting meanscorresponding to FIG. 5 but with another embodiment of a tensioningdevice.

FIG. 8 is a cross-sectional view of an upper grinding chamber takenalong the line VIII-VIII of FIG. 12.

FIG. 9 shows a partiallongitudinal section of the upper grinding chambersubstantially along the line IX-IX of FIG. 8.

FIG. 10 is a partial longitudinal sectional view similar to FIG. 9 butillustrates another arrangement of the conduits.

FIG. 11 illustrates diagrammatically a development of an annular body insection; and

FIG. 12 illustrates diagrammatically the arrangement of atemperature-adjusting device on a vibrating mill in accordance with theinvention.

The vibrating mill illustrated diagrammatically in FIG. 1 comprises twogrinding tubes 1 and 2 arranged in spaced parallel relation one abovethe other and secured by clamping stirrups 3 to a supporting framecomprising two brackets 4 connected with each other by a horizontallyarranged pipe 5. On the sides of the brackets 4 are attached the posts 6which by means of intermediate rubber cushions 7 attach the unitconsisting of the grinding chambers and the supporting frame to a rigidfoundation frame 8. As a result of the rubber cushion 7, the unitcomprising the grinding chambers and the supporting frame arevibratorily mounted. In the center between the two parallel andhorizontal grinding tubes 1 and 2, is arranged a vibratory drive whoseaxis extends parallel to the longitudinal axis of the grinding chambers.This vibratory drive comprises rotatably mounted and preferablyadjustably imbalanced weights which are arranged in the interior of thebrackets 4 and by a shaft disposed in the connecting pipe 5 areconnected with each other. These imbalanced weights are driven by auniversal joint shaft 9 driven by a not-illustrated motor.

A vertical feed pipe 10 for the material to be ground is connected tothe left-hand end of the upper grinding tube 1. At the other end of thegrinding tube 1 and at the lower side thereof is connected a discharge11 through which the material which. has been ground in the firstgrinding tube I is conducted by a vertical connecting pipe 12 into theright-hand end of the lower grinding tube 2 for further grinding. Theleft-hand end of the lower grinding tube 2 is provided with a discharge13 for the finely ground material which leaves the vibrating mill atthis point after it has traveled through both of the grinding tubes; oneafter the other.

Together with the material to be ground or by means of additional feedapertures, depending upon the particular type of the grinding operation,hot gases but preferably refrigerants-tor instance very cold fluids orgases-are introduced into the vibrating mill.

FIG. 2 illustrates a cross-sectional view of the lefthand portion of thegrinding tube 1. along the line IIII of FIG. 1, and one will recognizethe connection of the grinding tube 1 with the supporting frame. In thisparticular instance, the embodiment is provided with a heat-insulating,supporting device. The grinding chamher is formed by an inner grindingtube 15 in which additionally a so-called wearing plate 16 is slidablyinserted. The sectional view of FIG. 4 illustrates that the grindingtube on its outside is surrounded by an insulating jacket 30 which, forinstance, consists of polyurethane foam, and this insulating material isprovided on its outside with a thin sheet metal cover 31 for protectionagainst injuries.

Within the range of the connecting joint formed between the grindingtube 15 and the bracket 4, the grinding tube is provided on its outsidewith a band 18" which in uniform circumferential spaces is provided withrecesses in which substantially radially extending distance members 17are inserted which have heatinsulating properties. These distancemembers 17 are made for instance of polytetrafluoroethylene (PTFE) whichin addition to a thermal conductivity of only .21 kilocalories permeter, hour and centigrade has also a very high strength at lowtemperature and also a certain elasticity at this low temperature. Aclamping frame 18 is slidably moved in axial direction over the distancemember 17 and as shown, this clamping frame 18 is completely closed, butit is also possible to employ a subdivided clamping frame 18. Thisclamping frame 18 has the effect that the radial members 17 are biasedtoward the annular band 18" in radial direction in order to catch anexpected change in the diameter of the grinding tube 15 upon cooling. Aclamping stirrup 3 is applied to the upper half of the clamping frame18, so that the grinding tube 15 is brought into form-locking connectionwith the bracket 4 of the supporting frame. The clamping stirrup 3 isheld by bolts 19 in its operative position. The spaces extendinglengthwise between the individual distance members 17 may be filled withthe same insulating material of which the insulating jacket is made, forinstance with polyurethane foam. In place of the individual distancemembers 17, one may also employ a closed annular collar made, forinstance, of polytetrafluoroethylene.

The FIGS. 3 and 4 illustrate another embodiment of the connecting means.In these figures, the grinding tube 15 is provided on its outside andthe clamping frame on its inside, each with a grooved band 20 and 21,respectively, and made for instance of PTFE or EPT. The diameters of thegrinding tube 15 and the clamping frame 18 are so selected that betweenthe two grooved bands, an annular space is produced. In the oppositelyarranged grooved bands 20 and 21 are slidably inserted the distancemembers 22 which as shown in FIG. 4 have, for instance, a cylindricalform. These distance members 22 are made also of a material havingheat-insulating properties and preferably are also of a harder materialthan the jacket 30. The elements 22 may be made of ceramic materials,for instance, porcelain, quartz glass or other special technical glasseshaving a high resistance to pressure.

FIG. 4 also illustrates that there are provided suitably two double rowsof such distance members 22 at each joint between the grinding tube andthe supporting frame in order to distribute the clamping forces actingon the grinding tube over a surface as large as possible.

FIG. illustrates another embodiment of the invention in which theconnecting means between the grind ing tube and the supporting frame 4or a frame 48 respectively, comprises a flexible band 23 which embracesthe grinding tube 15 with tension and, viewed in circumferentialdirection, is alternately attached to the grinding tube and to thesupporting frame, so that the flexible band 23 assumes a zigzag form inthe hollow space between the grinding tube and the supporting frame. Theattachment of the flexible band 23 is effected in a very simple mannerin that the outer circumference of the grinding tube and the innercircumference of the frame 48 are provided with apertured radial lugs 24in the apertures of which are inserted bolts 25, and then the flexibleband 23 is threaded over these bolts 25. The frame 48 may becircumferentially divided into separate elements 48 as shown in FIG. 5.For the purpose of applying tension to one or more points of theflexible band, FIG. 6 illustrates the use of eccentrics 26 which takethe place of the bolts 25. When these eccentrics 26 are rotated in theproper direction and are then locked in position, the band 23 may betensioned in the desired manner.

FIG. 7 illustrates another manner in which the flexible band may betensioned. The clamping frame 49 is circumferentially subdivided into anumber of segments similarily to frame 48 in FIG. 5, and the outer ends29 of these segments are shaped conically, so that conical rings 27 whenpushed in axial direction toward each other by means of a screw 28engage the conical wall of the tensioning frame 49 and thereby the band23 is being tensioned.

FIG. 8 illustrates in cross-section a connection of the grinding tubewith the supporting frame in an embodiment in which the connectingelement is attached to the outside of the grinding tube. The connectingelement in FIG. 8 is formed by individual radial elements 32 which arespaced uniformly around the circumference of the grinding tube and arefixedly attached to the same. These radial connecting elements 32 extendthrough the insulating material 30. The outermost ends of the radialconnecting elements 32 are fixedly secured to a wide hollow cylindricalbody 33. The distance of the outer surface of this hollow cylindricalbody 33 from the outside of the grinding tube is so selected that it issomewhat greater than the thickness of the insulating jacket. The outersurface of the hollow cylindrical body 33 which forms a portion of theconnecting element engages with its lower portion a surface 34 asuitably semicircularly shaped recess in the connecting bracket 4 of thesupporting frame. The upper half of the hollow cylindrical body 33 iscovered by a clamping stirrup 3 and is secured by screws to the bracket4. The screws comprise preferably neckeddown bolts.

In the relatively thick wall of this hollow cylindrical body 33 areprovided conduits 35 which extend parallel to the longitudinal axisofthe grinding tube. Through these conduits 35 is conducted a flexibleheat carrier whose temperature is so adjusted that the temperature ofthe engagement surface 34 of the connecting element with the clampingstirrup and the connecting bracket remains within the range within whichthe clamping stirrup and the connecting bracket retain their strength.This means that when a refrigerantfor instance liquid nitrogenis addedto the material to be ground, it will be necessary to conduct throughthese conduits 35 a heating mediumfor instance, a hot liquid. On theother hand, when a heating agent is introduced into the grindingchamber, a suitable cooling medium must be passed through the conduits35 in order to maintain a temperature which keeps the material of theseparts of the grinding chamber connecting means in good condition.

In accordance with these features, a certain amount of heat will betransmitted by the radial members 32 into the grinding chamber orremoved therefrom. The losses of heat which occur in this manner arenegligible in view of the construction of the connecting means whichcombine the grinding chamber with the clamping stirrups.

FIG. 9 illustrates a longitudinal section taken along the line IXIX ofFIG. 8, and particularly this section is taken at the upper wall of thegrinding tube 1. This FIG. 9 illustrates that a preferred embodiment ofthe connecting means comprise two rows of connecting members 32 of whichthe inner ends engage the outer wall of the grinding-tube l5 and theouter ends engage the hollow cylindrical body 33. The conduits 35 forthe passage of a flowable heat carrier are arranged parallel to thelongitudinal axis of the hollow cylindrical body 33 and are connected onboth ends with each other by annular channels 36. One of these annularchannels 36 is connected with a feed line 37 and the other annularchannel 38 is connected with a discharge line 39 for the heat carrier.

FIG. 10 illustrates a sectional view similar to that of FIG. 8 but showsa different arrangement of the channels for the heat carrier. In thisembodiment, the ho]- low cylindrical bodycomprises two concentric rings40 and 41 of which the inner ring 40 which is rigidly secured to theouter ends of the radial members 32, has a smooth outer surface, whilethe outer ring 41 is provided on its inner surface with a helical groove43.

These two concentric rings 40, 41 are axially slidably pushed togetherand then are sealingly connected with each other. One end of the helicalchannel formed by the groove 43 is connected with a feed line and theother end is connected with the discharge line for the heat carrier.

In order to avoid a temperature drop from the left side toward the rightside within the clamping stirrup, it is advantageous when, as shown inthe sectional view, in the outer ring 41, two parallel grooves 42 and 43in the form of a double helix are provided, whereby one end of thechannel formed by the groove 42 is connected with a feed line 37' andthe end of the other channel formed by the groove 43 on the oppositeside is connected with a feed line 37" for the heat carrier. In thismanner, there will be produced over the entire axial length substantialuniform temperature over the engagement surface. The discharge lines aredesignated by 39 and 39", respectively.

As illustrated in the diagrammatic development of a ring with parallelchannels in FIG. 11, they all extend in the axial direction of the ring.The principle shown in FIG. may also be applied when all of the channelsare parallel to one another. This is accomplished in that the ends ofthe channels are alternately connected with one end, then the nextchannel with the other end with a feed line for the feed carrier.

In the event that a refrigerant is to be introduced into the grindingchamber, one may employ in place of the channels which should contain aheated fluid also an electric resistance heating means. In such aconstruction, suitable electric resistance rods are arranged parallel toeach other or in helical manner in the hollow cylindrical body either byinsertion or by casting and then the ends of these resistances areconnected to a source of electric current.

FIG. 12 illustrates diagrammatically in what manner a thermometer probe44for instance a thermo ele' mentis mounted in the clamping stirrups.Such a thermometer probe 44 is connected with an electric adjustingdevice 45, which is so constructed and adjusted that a predetermineddesired temperature will be main tained in the clamping stirrups.Accordingly, the adjusting device cooperates with another device such asa valve 46 or a pump which is arranged in a pipeline leading to aheating or cooling device 47 respectively. If, for instance, thematerial is ground in the grinding tube at a low temperature, then aheated fluid is used as heat carrier, while in the event that additionalheat is introduced into the grinding tube, a cooling agent serves toheat as heat carrier so as to hold the clamping stirrups at a constanttemperature.

The principle of the invention is not limited to the disclosedembodiment of the vibrating mill and also is not limited to thedescribed construction of the connecting elements, and the arrangementof the conduits in the same.

What we claim is:

I. A vibratory mill, comprising at least one elongated comminutingmember, a heat-insulating jacket surrounding said comminuting member, aframe supportingly connected with said comminuting member, meansoperatively connected with said frame for imparting vibratory movementto the same, said frame including clamping means surrounding saidcomminuting member and comprising a first annular band means concentricwith said comminuting member and spaced radially outwardly therefrom, asecond annular band means concentric with and engaging said comminutingmember and a plurality of circumferentially spaced distance membersdisposed in the annular space between said first annular band means andsaid comminuting member being supported by said second annular bandmeans and supporting'ly extending between said first annular band meansand said comminuting member to support the comminuting member.

2. A vibratory mill according to claim 1, in which saidcircumferentially spaced distance members are made of a harder materialthan said concentrically arranged annular bands.

3. A vibratory mill according to claim 1, in which saidcircumferentially spaced distance members are made of a ceramicmaterial, a quartz glass or a tempered glass having high strength.

4. A vibratory mill, comprising at least one elongated comminutingmember, a heat-insulating jacket sur rounding said comminuting member, aframe supportingly connected with said comminuting member, meansoperatively connected with said frame for imparting vibratory movementto the same, said frame including clamping means surrounding saidcomminuting member and comprising an annular band member con centricwith said comminuting member and spaced therefrom, attachment meanssecured to the outer wall of said comminuting member, and a flexible andsubstantially unstretchable band attached at circumferentially spacedpoints alternately to said annular band member and said attachment meansin the annular space formed between said comminuting member and saidannular band member.

5. A vibratory mill according to claim 4, including tensioning meansconnected with said flexible band.

6. A vibratory mill, comprising at least one elongated comminutingmember, a heat-insulating jacket surrounding said comminuting member, aframe supportingly connected with said comminuting member, meansoperatively connected with. said frame for imparting vibratory movementto the same, said frame including an annular band member concentric withsaid comminuting member and spaced therefrom, band means secured to theouter wall of said comminuting member, and a plurality ofcircumferentially spaced radially extending distance members engaging ontheir radial inner ends with the band means on the outer wall of thecomminuting member and at the radial outer

1. A vibratory mill, comprising at least one elongated comminutingmember, a heat-insulating jacket surrounding said comminuting member, aframe supportingly connected with said comminuting member, meansoperatively connected with said frame for imparting vibratory movementto the same, said frame including clamping means surrounding saidcomminuting member and comprising a first annular band means concentricwith said comminuting member and spaced radially outwardly therefrom, asecond annular band means concentric with and engaging said comminutingmember and a plurality of circumferentially spaced distance membersdisposed in the annular space between said first annular band means andsaid comminuting member being supported by said second annular bandmeans and supportingly extending between said first annular band meansand said comminuting member to support the comminuting member.
 2. Avibratory mill according to claim 1, in which said circumferentiallyspaced distance members are made of a harder material than saidconcentrically arranged annular bands.
 3. A vibratory mill according toclaim 1, in which said circumferentially spaced distance members aremade of a ceramic material, a quartz glass or a tempered glass havinghigh strength.
 4. A vibratory mill, comprising at least one elongatedcomminuting member, a heat-insulating jacket surrounding saidcomminuting member, a frame supportingly connected with said comminutingmember, means operatively connected with said frame for impartingvibratory movement to the same, said frame including clamping meanssurrounding said comminuting member and comprising an annular bandmember concentric with said comminuting member and spaced therefrom,attachment means secured to the outer wall of said comminuting member,and a flexible and substantially unstretchable band attached atcircumferentially spaced points alternately to said annular band memberand said attachment means in the annular space formed between saidcomminuting member and said annular band member.
 5. A vibratory millaccording to claim 4, including tensioning means connected with saidflexible band.
 6. A vibratory mill, comprising at least one elongatedcomminuting member, a heat-insulating jacket surrounding saidcomminuting member, a frame supportingly connected with said comminutingmember, means operatively connected with said frame for impartingvibratory movement to the same, said frame including an annular bandmember concentric with said comminuting member and spaced therefrom,band means secured to the outer wall of said comminuting member, and aplurality of circumferentially spaced radially extending distancemembers engaging on their radial inner ends with the band means on theouter wall of the comminuting member and at the radial outer ends withthe band member of the frame, and insulation material in the spacesbetween said distance members.